Another metasearch service that some would suggest is worth throwing into the pile is Google - although how important a player it is for hotels or flights will inevitably ignite very polarised opinions.

On Google, Hafner says it is "by far the biggest" in terms of brand, but that it is still ten to 15 years behind Kayak when it comes to functionality.

Cheeky swipes aside, suggesting that the aforementioned five should somehow be reduced to just two global players is, to some, an extraordinary proposition.

And, inevitably, throws up a large range of possibilities and permutations.

Following Hafner's comments earlier this week in Singapore (but unlikely to be connected), a report with the inevitable "people familiar with the situation" sources on Bloomberg suggested that the Priceline Group would be interested in acquiring Skyscanner, or that the Edinburgh, UK-based company is gearing up to list on the public markets.

The first scenario - Priceline Group buying Skyscanner - would be, at least from a PR perspective, an unfortunate one given that Hafner had labelled his arch rival "goons" on-stage.

The second has been speculated about for at least five years, probably more.

Earlier, on the same day as Hafner's remarks, a panel of travel search brands, including Wego, Hotelscombined, Travel.jp and TripAdvisor, also had the "consolidation" angle thrown at it.

Qunar co-founder Fritz Demopoulos (who now runs Queen's Road Capital) was the only member of the group that would speak openly about how the market might evolve.

"There are a lot of metasearch brands out there," he says, "so it makes sense."

But, adding somewhat tantalisingly:

"The fact that someone hasn't pulled the trigger yet is telling."

Share this quote

And this is where the debate gets somewhat controversial.

There are some who believe that many of the travel search brands in the market (considered "second tier") simply do not have the volume or focus on a particular sector (hotels or flights) to catch the eye of others in a consolidation scenario where the outlay would warrant the effort or financial outlay.

But what about the main players, those that Hafner places in the five-down-to-two market?

It seems inconceivable that such a major shrinking of the ownership of the market could take place easily and quickly.

This, whilst it may happen at some point, is very much a long-term play.

There is also the widely held belief that the power rests in those that have scale in the hotel search market, rather than flights, a vertical which is well-known for having slimmer margins than its accommodation counterpart.

As one observer notes:

"The most attractive brands are going to be those that have created sizeable businesses, with plenty of room for further growth in a specific sector, or have managed to build a substantial presence in a particular region - rather than those that have spread themselves thinly."

Share this quote

What is very much a reality is the strong likelihood of Trivago heading for its own foray into the public financial markets in the near future.

As Lorraine Sileo, senior vice president of research of Phocuswright, says during an on-stage discussion this week:

"We should keep an eye of the Trivago IPO. That will be a good signal of the value of the market."

Share this quote

Travel search spent a long time trying to establish itself as more than the noisy child of the industry, but as an important part of the travel marketing and distribution ecosystem - the turning point probably being when the Priceline Group bought Kayak for $1.8 billion in November 2012.

But in the following four years, Expedia Inc (through its $632 million investment in Trivago) and TripAdvisor (with its own significant switch to hotel metasearch) have also woken up and realised that there is an awful lot on the table that can be used in the increasingly global power play in travel.

Travel search is perhaps on the verge of truly growing up, leaving home, and heading for higher education with some of its powerful friends.